The present invention relates to methods for producing subterranean formation treatment fluids with efficient fluid loss control material suspendability.
Hydrocarbon producing wells are typically formed by drilling a wellbore into a subterranean formation. A drilling fluid is circulated through a drill bit within the wellbore as the wellbore is being drilled. The drilling fluid is circulated back to the surface of the wellbore with drilling cuttings for removal from the wellbore. The drilling fluid maintains a specific, balanced hydrostatic pressure within the wellbore, permitting all or most of the drilling fluid to be circulated back to the surface. However, the hydrostatic pressure of the drilling fluid may be compromised if the drill bit encounters certain unfavorable subterranean zones, such as low pressure zones caused by natural fissures, fractures, vugs, or caverns, for example. Similarly, if the drill bit encounters high-pressure zones or crossflows, for example, an underground blowout may occur. The compromised hydrostatic pressure of the drilling fluid causes a reduction of drilling fluid volume returning to the surface, termed “lost circulation.” The unfavorable subterranean zones contributing to lost circulation are termed “lost circulation zones.” In addition to drilling fluids, other operational treatment fluids, such as fracturing fluid, may be lost to the subterranean formation due to fluid loss. The term “lost circulation” refers to loss of a drilling fluid, while the term “fluid loss” is a more general term that refers to the loss of any type of fluid into the formation. As a result, the service provided by the treatment fluid is often more difficult to achieve or suboptimal.
The consequences of lost circulation or fluid loss can be economically and environmentally devastating, ranging from minor volume loss of treatment fluids, to delayed drilling and production operations, to an underground well blowout. Therefore, the occurrence of fluid loss during hydrocarbon well operations typically requires immediate remedial steps. Remediation often involves introducing a composition into the wellbore to seal unfavorable subterranean zones and prevent leak off of treatment fluids within the formation to the unfavorable zones. Such compositions are generally referred to as “fluid loss control materials” or “FLCM.”
In fluid loss control treatments, the specific gravity of the FLCMs may be high in relation to the treatment fluids in which they are suspended for transport and deposit at a lost circulation zone. Therefore, FLCMs may settle out of the treatment fluid such that they are insufficiently deposited at a lost circulation zone and unable to seal the zone and prevent or control lost circulation. For example, in some instances the FLCMs may so settle in the treatment fluid that they are lost to portions of the subterranean formation that do not require lost circulation controlling. In other instances, the FLCMs may so settle that there are not a sufficient number of FLCMs to control a lost circulation zone. Therefore, a subterranean formation treatment fluid that is able to substantially uniformly suspend FLCM particulates may be beneficial to one of ordinary skill in the art.